1. Field of the Invention
The present invention relates to an information processing apparatus, a control method therefor, and a storage medium storing a program for executing the control method.
2. Description of the Related Art
A secondary battery such as a lithium battery or a nickel hydride battery is used as a temporary backup power source at shutdown of power supply from a power source. For example, an image processing apparatus has a secondary battery that supplies backup power enabling a volatile memory of the apparatus such as a DRAM to retain facsimile image data, etc. at shutdown of power supply from, e.g., a commercially available AC power source to the image processing apparatus.
Such a backup secondary battery is provided for accidental short-time power shutdown such as power outage, and is generally charged to become a predetermined charged state, e.g., a fully-charged state. However, if the fully-charged secondary battery is further charged to an overcharged state, the battery performance is deteriorated. Accordingly, techniques have been proposed in which when a fully-charged state of the secondary battery is detected, a shift is made to trickle charge where the battery is charged with an amount of current for compensating only for self-discharge of the battery.
In these techniques, when the battery voltage reaches a predetermined voltage, a fully-charged state is detected and a shift is made to the trickle charge. However, a relation between battery voltage and battery charge state varies depending on peripheral temperature, and accordingly, a fully-charged state cannot be properly detected in some cases without using a temperature sensor. Thus, there has been proposed a technique for starting normal charge at power-on and for making a changeover from normal charge to trickle charge when a predetermined time period (e.g., 12 hours to 16 hours) has lapsed from the start of the normal charge.
Another proposed technique is to reduce power consumption by not performing data backup at shutdown of power supply or at power-saving in a case where there is no backup object data such as facsimile image data (see, for example, Japanese Laid-open No. H08-129511).
However, it takes several hours for the secondary battery to be charged by the normal charge to a fully-charged state. Accordingly, if an image processing apparatus or the like is started up in a state where the secondary battery is almost discharged, a time period over which a data backup operation can be performed becomes extremely short immediately after the start of the apparatus, so that the backup power source function of the secondary battery is impaired.
Also known is quick charge in which an amount of charge current is increased as compared to that in the normal charge to thereby shorten a time period required for battery charge. However, there is a fear that overcharge is caused, if the quick charge using a large amount of charge current per unit time is performed in a state where the battery charge state cannot be detected with accuracy due to a change in peripheral temperature.